Half-tone screen



(No-Model.) 2 Sheets-Sheet 1.

M. LEVY.

HALF TONE SCREEN.

No. 591,653. Patented Oct 12,1897.

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(No Model.) 2 Sheets-Shet 2.

M. LEVY.

HALF TONE SGREEN.

Patented Oct. 12, 1897.

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UNITED STATES PATENT OFFICE.

MAX'LEVY, OF PHILADELPHIA, PENNSYLVANIA.

HALF-TQYNIE SCYREE'N.

SPECIFICATION forming part ofLetters Patent No. 591,653, dated Octcber 12, 1 89 7; Application filed June 30, 1896. SerialNo. 697,60i3. (No model.) I 7 To all whom it may concern: I

Be it known that I, MAX LEVY, a citizen of the United States of America, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Screens forMakingPhotomechanical Printii'ig-Plates; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art iowhich it appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of thisspecification.

This invention relates to photomechanical gratings or screens for producing printing.

surfaces in carrying out the half-tone process; ,and it consists in a'diiferent arrangement of theapertures of the screen by-means of which it becomes possible to make negatives as required for half-tone printing on gelatin dry plates and of a quality and with a facility which it is impossible to obtain with the aid of a screen as heretofore produced. In making a half-tone plate with the aidof a screen what takes place is that through each apertur'e'in the screen is formed a distinct image of the lens-aperture, and the half-tone 'negative'consists of a regular series of reproduced'images of the lens-aperture.

In order to develop these images clearly, it

is necessary to resort to'th'e'use of vigorous intensifiers which shall have the property of building up to the maximum opacity parts of:

the image having a relatively weak'deposit as developed. It'will-be obvious that in an image of a square placed as above indicated,

formed through an apertur'e'in the ordinary cross-lined screen, the corners of the image i withstanding that a is in form a full ima e of the aperture in the lens, will have allits corners so weak as' to show but an apparently round or oct;agonal-imagebefore intensification. At the same timethat the intensification develops these separate images'by building up the weaker parts in greater proportion than the denser ones the effect of the entire picture suffers material loss, as is well attested by all practical workers in this field.

With a screen having apertures arranged with their corners adjacent it will be'app'arent that with the same conditionsas' 'indicated as the most favorable for the screen formedof cross-lines the separate images of the lens-aperture formed through these apertures in the screen will liedirectly in'the'dire'ction'of the sidesof these apertures, and that as a consequence any'portion of the image not of fullstrength will be equal on all sides and the images will fully'overlap each other exactly at the point where this overlapping is necessary to give the 'eifeet of a dot in'the high light of the reproduction, and for the same amount of increase of size of image over screen a'perture" in this arrangement the maximum excesswould be but one-half of what is required 'in 'thej "present screen, p

By theaid of'a screen, 'whichIjvilLdescribe, it is possible to make *a' so -called screen-negative i on a'gelatin dry plate'that will haveapprox imat ely the same printing qu'alities'as the best wet c'ollo'dion negative that can be produced with'a screenformed of cross-line's, and the result 'insuch a; negative will have far more'of the delicate gradations of light and shade of the original than will the "wet-'c'ollodi'on negativeas atpresei'it produced. The improved screen will-alsbbe of advantage over the present form in connection with the wet-collodion process as at present employed. The results to be produced by these screens are similar in general character to those produced with cross-line screens as set forth in the patents issued to meFebruary 21, 1893, No. 492,333, and June 19, L394, No. 521,659 but a more delicate gradaftion'of light and shade in the negative will always be produced with the new screen than with the form in general use.

In carrying out my invention I may use a screen constructed in a variety of ways, either by photography, by ruling opaquelines ,on a transparent ground, or by ruling transparent lines through an opaque ground, one of the leading features of my improved screen being in the fact that it presents opaque blocks or squares of such size that their corners overlap.

In the accompanying drawings, Figure 1 is a view showing a screen made by ruling opaque lines on a transparent ground, and in produc- 1 in g such a screen two plates are employed and ruled, as shown in Figs. 1 and 1", these plates being superimposed upon each other, so that the rulings will cross each other at forty-five degrees, and thus produce large rectangular opaque squares, adjacent to which are rela-.

tivel y smaller transparent squaresthe opaque squares being arranged so that the corners? overlap each other.

screen formed by ruling or producing trans- Fig. 2 shows one style of j agonal line, the diagonal lines being spaced differently to give different results.

In making a screen as shown in Fig. l Irule 11 p n a a pa n p as g a sin s a and a, which cross each other at right angles, these lines being spaced equidistant. I then rule a second plate, as shown in Fig. 1-, with lines I) and b, which are of a greater distance part han he li a n and also o greater thickness, thus producing two plates having opaque crosslines, which are placed one upon the other, so that the several lines will cross each other at an angle of forty five degrees, thereby producing a gratin gor screen which is practically made up of aserios .Qf opaque squares the corners of which overlap each other and provide intermediate eottllgular transparent apertures the corners of which are adjacent to each other.

It will be noted that in the construction of a screen as hereinbei'ore described there is a p eponde anc of opacity o he plate relative to the transparent ground.

The screen shown in Fig. 2 is produced by ng th n p qu r und or y rho-- tography, and if made by ruling the two plates are placed together to provide rectangular transparent apertures and opaque squares the corners of which overlie each other. To pro duce this screen, the transparent lines of the two plates are of equal width and equally V spaced, said lines o and c crossing each other at right angles, and as a consequence leave upon the plates opaque squares all of the same size. When these plates are placed one upon the other face to face, they produce the screen shown in Fig. 2, in which the. corners of the opaque squares overlap each other and of their diagonals.

- intersecting the center of the squares.

in which the transparent squares are much.

nearer together than could be produced bya screen ruled as in Figs. 1 and 1 Figs. 3 and 4 are modified forms of Fig. 2, the completed plates presenting overlapping opaque blocks forming square apertures combined with oblong apertures, said square and oblong apertures alternating in the direction The screen shown in Fig. 3 is made up of two plates, Figs. 3 and 3,

one having vertical rulings (I, crossed at right angles by rulings d of a greater width than the rulings d, and the other plate having rulings d (1 both of which are of the same width as 'the rulingd and equally spaced. When the two plates are placed one upon the other, they will produce a screen or grating presenting a series of relatively large oblong apertures arranged horizontally according to their greatest width, and a second series of smaller oblong apertures arranged vertically, the larger and smaller apertures suc-- length, and in Fig. 4 the horizontal transparent lines e are of greater width than the vertical lines 6 to present opaque blocks in.

horizontal series, according to their greatest width. When these two plates are placed one upon the other, they will present a screen, Fig. l, in which there are relatively larger an ma ler tran parent Squares suc each other alternately in the direction of their diagonals, the corners of the oblong opaque blocks ofthe separate plates overlapping each other.

In Fig. 5 Ihave shown a screen in which the plate Fig. 5 is rul d with cross-lines f and f through an opaque ground, leaving opaque In Fig. 4 one of the plates is ruled blocks or squares, and said squares are crossed diagonally by narrow rulings f said rulings The ulings up n h p a ig- 5b a m ar presenting cross-lines and diagonal lines, but

' in this case the diagonal lines cross the opaque blocks to one side of their center, as shown, thereby presenting upon the plate Fig. 5

r an ula opaq e lo ks of q al e an upon the plate Fig. 5 triangular opaque blocks of difierent sizes. When these plates are placed one upon the other, they produce the screen'shown in Fig. 5, presenting trans- Parent squares and intermediate oblong apertures the ends of which are formed by the overlapping corners of the opaque triangles.

Fig.6 is a modification of Fig. 5, and in this case the plates Figs. (F and 6", which make up the screen, are ruled with transparent lines upon an opaque ground, the crosslines g and g being of diderent width to first present oblong blocks, and said blocks are horizontally.

crossed diagonallyby thinner lines g which cross the center of said blocks, as shown. In Fig. 6 the oblong blocks are arranged vertically according to their greatest width, and in Fig. 6 said oblong blocks are arranged By this arrangement the two plates when placed together present relativel y larger and smaller transparent blocks succeeding each other alternately in the direction of their diagonals, and between said transparent blocks, vertically and horizontally, are formed oblong apertures positioned diagonally.

Screens constructed as herein shown and described obviate the objection appertaining to the printing-surface, wherein both the black and white dots are connected by thin lines.

YVith my improved screen the dots appear in their proper size and are disconnected to produce a superior printing-surface, and the screen may be termed automatic, as it does not depend to the same extent for successful use upon the screen-aperture.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. A grating or screen presenting transparent rectangular apertures on an opaque ground, said apertures being so positioned that they succeed each other in the direction of their corners, the opaque portions of the screen being formed of larger blocks the corners of which overlap, substantially as shown.

2. A grating or screen made up to present a series of rectangular transparent apertures adjacent to which are rectangular opaque portions the corners of which overlie each other, substantially as shown, whereby a grating or screen is produced having a less proportion of transparency than opacity.

3. A grating or screen made up of a pair of plates each having different rulings so that when positioned one adjacent to the other, the completed screen will consist of transparent rectangular apertures on an opaque ground, said apertures succeeding each other in the direction of their diagonals, and opaque portions formed of larger blocks the corners of which overlap.

4. A grating or screen for the purpose set forth made up to present a series of rectangular transparent apertures which succeed each other in the direction of their diagonals and are separated by opaque blocks which also succeed each other in the direction of their diagonals, each succeeding opaque portion being intersected by a transparent line, substantially as shown.

5. A grating or screen presenting opaque rectangular portions the corners of which overlap, said opaque portions being intersected or divided to provide transparent portions which are so arranged as to be alternately at right angles with each other, and intermediate transparent rectangular portions which succeed each other in the direction of their diagonals.

In testimony whereof I affix my signature in presence of two witnesses.

MAX LEVY. Witnesses:

E. L. WoonwARD,

C. A. I-IAUssER. 

